Biology Slide 1 of 14

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1 Biology 1 of 14

2 10 1 Cell Growth 2 of 14

3 10 1 Cell Growth Limits to Cell Growth What problems does growth cause for cells? 3 of 14

4 10 1 Cell Growth Limits to Cell Growth Limits to Cell Growth The larger a cell becomes, the more demands the cell places on its DNA. In addition, the cell has more trouble moving enough nutrients and wastes across the cell membrane. 4 of 14

5 10 1 Cell Growth Limits to Cell Growth The rate at which food, oxygen, water, and wastes are moved in and out of the cell is dependent on the surface area of the cell. The rate at which food, oxygen, and water are used and waste is produced depends on the cell s volume. 5 of 14

6 10 1 Cell Growth Limits to Cell Growth Ratio of Surface Area to Volume As the length of a cell increases, its volume increases faster than the surface area. The decrease in the cell s ratio of surface area to volume makes it more difficult for the cell to move needed materials in and waste products out quickly enough for the cell to survive. 6 of 14

7 10 1 Cell Growth Limits to Cell Growth 7 of 14

8 10 1 Cell Growth Division of the Cell Division of the Cell Before it becomes too large, a growing cell divides forming two daughter cells. The process by which a cell divides into two new daughter cells is called cell division. 8 of 14

9 10 1 Continue to: - or - Click to Launch: 9 of 14

10 10 1 As a cell increases in size, which of the following increases most rapidly? a. surface area b. volume 10 of 14

11 10 1 If an imaginary cube-shaped cell has a length of 6 cm, its ratio of surface area to volume is a. 1 : 1. b. 6 : 1. c. 36 : 1. d. 1 : of 14

12 10 1 The process by which a cell divides into two new daughter cells is called a. cell growth. b. cell division. c. DNA replication. d. cell multiplication. 12 of 14

13 10 1 When one cell divides in two, what happens to the surface area to volume ratios in the new cells? a. There is no change in the amount of material exchanged. b. Each new cell can exchange more material than the original cell. c. Each new cell can exchange less material than the original cell. d. The two new cells cannot be compared to the original cell. 13 of 14

14 10 1 When a growing cell undergoes cell division, each new cell gets a. half the DNA from the original cell. b. twice as much DNA as the original cell. c. a random sample of the DNA in the original cell. d. a full copy of all the DNA in the original cell. 14 of 14

15 END OF SECTION

16 Prentice Hall Biology 16 of 38

17 10-2 Cell Division 17 of 38

18 10-2 Cell Division In eukaryotes, cell division occurs in two major stages. The first stage, division of the cell nucleus, is called mitosis. The second stage, division of the cell cytoplasm, is called cytokinesis. 18 of 38

19 10-2 Cell Division Chromosomes Chromosomes Genetic information is passed from one generation to the next on chromosomes. Before cell division, each chromosome is duplicated, or copied. 19 of 38

20 10-2 Cell Division Chromosomes Each chromosome consists of two identical sister chromatids. Sister chromatids Each pair of chromatids is attached at an area called the centromere. Centromere 20 of 38

21 10-2 Cell Division Chromosomes When the cell divides, the chromatids separate. Each new cell gets one chromatid. 21 of 38

22 10-2 Cell Division The Cell Cycle What are the main events of the cell cycle? 22 of 38

23 10-2 Cell Division The Cell Cycle The Cell Cycle The cell cycle is the series of events that cells go through as they grow and divide. Interphase is the period of growth that occurs between cell divisions. 23 of 38

24 10-2 Cell Division The Cell Cycle During the cell cycle: a cell grows prepares for division divides to form two daughter cells, each of which begins the cycle again 24 of 38

25 10-2 Cell Division The Cell Cycle The cell cycle consists of four phases: G 1 (First Gap Phase) S Phase G 2 (Second Gap Phase) M Phase 25 of 38

26 10-2 Cell Division Events of the Cell Cycle Events of the Cell Cycle During G 1, the cell increases in size synthesizes new proteins and organelles 26 of 38

27 10-2 Cell Division Events of the Cell Cycle During the S phase, chromosomes are replicated DNA synthesis takes place Once a cell enters the S phase, it usually completes the rest of the cell cycle. 27 of 38

28 10-2 Cell Division Events of the Cell Cycle The G 2 Phase (Second Gap Phase) organelles and molecules required for cell division are produced Once G 2 is complete, the cell is ready to start the M phase Mitosis 28 of 38

29 Events of the Cell 10-2 Cycle Cell Division Events of the Cell Cycle Cell Cycle 29 of 38

30 10-2 Cell Division Mitosis What are the four phases of mitosis? 30 of 38

31 Mitosis 10-2 Cell Division Mitosis Biologists divide the events of mitosis into four phases: Prophase Metaphase Anaphase Telophase 31 of 38

32 10-2 Cell Division Mitosis Mitosis 32 of 38

33 10-2 Cell Division Mitosis Section 10-2 Prophase Spindle forming Prophase Centromere Chromosomes (paired chromatids) Click to Continue 33 of 38

34 10-2 Cell Division Mitosis Prophase Spindle forming Prophase is the first and longest phase of mitosis. The centrioles separate and take up positions on opposite sides of the nucleus. Centromere Chromosomes (paired chromatids) 34 of 38

35 10-2 Cell Division Mitosis The centrioles lie in a region called the centrosome. The centrosome helps to organize the spindle, a fanlike microtubule structure that helps separate the chromosomes. Spindle forming Centromere Chromosomes (paired chromatids) 35 of 38

36 10-2 Cell Division Mitosis Chromatin condenses into chromosomes. The centrioles separate and a spindle begins to form. The nuclear envelope breaks down. Spindle forming Centromere Chromosomes (paired chromatids) 36 of 38

37 10-2 Cell Division Mitosis Metaphase Centriole Spindle Centriole Metaphase Click to Continue 37 of 38

38 10-2 Cell Division Mitosis Metaphase The second phase of mitosis is metaphase. The chromosomes line up across the center of the cell. Microtubules connect the centromere of each chromosome to the poles of the spindle. Centriole Spindle 38 of 38

39 10-2 Cell Division Mitosis Anaphase Individual chromosomes Anaphase 39 of 38

40 10-2 Cell Division Mitosis Anaphase Anaphase is the third phase of mitosis. The sister chromatids separate into individual chromosomes. The chromosomes continue to move until they have separated into two groups. Individual chromosomes 40 of 38

41 10-2 Cell Division Mitosis Telophase Nuclear envelope reforming Telophase 41 of 38

42 10-2 Cell Division Mitosis Telophase Telophase is the fourth and final phase of mitosis. Chromosomes gather at opposite ends of the cell and lose their distinct shape. 42 of 38

43 10-2 Cell Division Mitosis A new nuclear envelope forms around each cluster of chromosomes. 43 of 38

44 10-2 Cell Division Cytokinesis Cytokinesis Cytokinesis 44 of 38

45 10-2 Cell Division Cytokinesis During cytokinesis, the cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes. 45 of 38

46 10-2 Cell Division Cytokinesis In plants, a structure known as the cell plate forms midway between the divided nuclei. Cell plate Cell wall 46 of 38

47 10-2 Cell Division Cytokinesis The cell plate gradually develops into a separating membrane. A cell wall then begins to appear in the cell plate. 47 of 38

48 10-2 Continue to: - or - Click to Launch: (must have QuickTake software installed on the computer you are using for this presentation) 48 of 38

49 10-2 The series of events that cells go through as they grow and divide is called a. the cell cycle. b. mitosis. c. interphase. d. cytokinesis. 49 of 38

50 10-2 The phase of mitosis during which the chromosomes line up across the center of the cell is a. prophase. b. metaphase. c. anaphase. d. telophase. 50 of 38

51 10-2 Cytokinesis usually occurs a. at the same time as telophase. b. after telophase. c. during interphase. d. during anaphase. 51 of 38

52 10-2 DNA replication takes place during the a. S phase of the cell cycle. b. G 1 phase of the cell cycle. c. G 2 phase of the cell cycle. d. M phase of the cell cycle. 52 of 38

53 10-2 During mitosis, sister chromatids separate from one another during a. telophase. b. interphase. c. anaphase. d. metaphase. 53 of 38

54 END OF SECTION

55 Biology 55 of 18

56 10-3 Regulating the Cell Cycle 56 of 18

57 10-3 Regulating the Cell Cycle Controls on Cell Division Controls on Cell Division Experiments show that normal cells will reproduce until they come into contact with other cells. When cells come into contact with other cells, they respond by not growing. This demonstrates that controls on cell growth and division can be turned on and off. 57 of 18

58 10-3 Regulating the Cell Cycle Controls on Cell Division Contact Inhibition 58 of 18

59 10-3 Regulating the Cell Cycle Cell Cycle Regulators How is the cell cycle regulated? 59 of 18

60 10-3 Regulating the Cell Cycle Cell Cycle Regulators Cell Cycle Regulators The cell cycle is regulated by a specific protein. The amount of this protein in the cell rises and falls in time with the cell cycle. Scientists called this protein cyclin because it seemed to regulate the cell cycle. Cyclins regulate the timing of the cell cycle in eukaryotic cells. 60 of 18

61 10-3 Regulating the Cell Cycle Cell Cycle Regulators Cyclins were discovered during a similar experiment to this one. A sample of cytoplasm is removed from a cell in mitosis. The sample is injected into a second cell in G 2 of interphase. As a result, the second cell enters mitosis. 61 of 18

62 10-3 Regulating the Cell Cycle Cell Cycle Regulators Internal Regulators Proteins that respond to events inside the cell are called internal regulators. Internal regulators allow the cell cycle to proceed only when certain processes have happened inside the cell. 62 of 18

63 10-3 Regulating the Cell Cycle Cell Cycle Regulators External Regulators Proteins that respond to events outside the cell are called external regulators. External regulators direct cells to speed up or slow down the cell cycle. 63 of 18

64 10-3 Regulating the Cell Cycle Uncontrolled Cell Growth Uncontrolled Cell Growth Cancer is a disorder in which some of the body's own cells lose the ability to control growth. How are cancer cells different from other cells? 64 of 18

65 10-3 Regulating the Cell Cycle Uncontrolled Cell Growth Kidney cancer cells Healthy human T-cell. They are also able to recognize and eliminate some tumor cells and cells infected with herpes viruses. Cancer cells do not respond to the signals that regulate the growth of most cells. 65 of 18

66 10-3 Regulating the Cell Cycle Uncontrolled Cell Growth Cancer cells divide uncontrollably and form masses of cells called tumors that can damage the surrounding tissues. Cancer cells may break loose from tumors and spread throughout the body, disrupting normal activities and causing serious medical problems or even death. 66 of 18

67 10-3 Regulating the Cell Cycle Killing Cancer Cells 67 of 18

68 10-3 Continue to: - or - Click to Launch: 68 of 18

69 10-3 The cell cycle is believed to be controlled by proteins called a. spindles. b. cyclins. c. regulators. d. centrosomes. 69 of 18

70 10-3 Proteins that respond to events inside the cell are called a. internal regulators. b. external regulators. c. cyclins. d. growth factors. 70 of 18

71 10-3 Once a multicellular organism reaches adult size, the cells in its body a. stop dividing. b. grow and divide at different rates, depending on the type. c. have the same life span between cell divisions. d. undergo cell division randomly. 71 of 18

72 10-3 One effect of an internal regulator is that a cell will not begin mitosis until a. it becomes too large. b. the cell s growth is stimulated. c. it is in physical contact with other cells. d. all its chromosomes have been replicated. 72 of 18

73 10-3 One factor common to almost all cancer cells is a. a lack of cyclin. b. a defect in gene p53. c. exposure to tobacco smoke. d. exposure to radiation. 73 of 18

74 END OF SECTION